Nozzle assemblies, also referred to as stators or stator assemblies, are commonly included in various forms of commercial equipment. For example, compressors and turbines generally include alternating stages of nozzle assemblies and rotating blades as is known in the art. Each nozzle assembly generally comprises one or more airfoils connected to an outer sidewall and an inner sidewall. The outer sidewall is typically fixedly attached to a stationary component, such as a shroud or casing, and the inner sidewall is typically proximate to one or more rotating components, such as a rotor or rotor wheel. In this manner, the outer sidewall provides a cantilevered support for the nozzle assembly, with the airfoils extending radially inward substantially perpendicular to a fluid flow to direct the fluid flow onto a downstream stage of rotating blades or buckets.
Over time, the fluid flow over the nozzle assemblies may plastically deform the shape and/or profile of the nozzle assemblies, a condition also known as “creep.” The effects of creep is one of the main failure mechanisms in a gas turbine having cantilevered nozzle assemblies. Specifically, over time the fluid flow over the nozzle assemblies causes the inner sidewall to move in the direction of the fluid flow. Deflection of the inner sidewall may reduce the clearance between the inner sidewall and the rotating components, restricting cooling flow between the inner sidewall and the rotating components. The reduced cooling flow between the inner sidewall and the rotating components may lead to excessive temperatures and ultimately failure of the rotating components. In addition, excessive creep may cause the stationary nozzle assemblies to crack and/or deflect into the rotating components, causing substantial damage and requiring costly repairs to both the stationary nozzle assemblies and the rotating components. As a result, the axial length of the nozzle assemblies may be required to increase in order to reduce the amount or effect of creep that occurs in the nozzle assemblies over the expected life, resulting in a corresponding increase in the length of the compressor or turbine.
Various systems and methods are known in the art for reducing or preventing the effects of creep in nozzle assemblies. For example, superalloys that are more resistant to the effects of creep may be used in the manufacture of the airfoils and/or sidewalls of the nozzle assemblies. Alternately, or in addition, the shape and/or thickness of the airfoil and/or sidewalls may be increased to reduce the amount of creep that occurs over time. Lastly, a cooling medium may be supplied inside the airfoil to reduce the surface temperature of the nozzle assemblies to reduce creep. Although these systems and methods have proven effective at reducing the effects of creep, the cost to implement these systems and methods may be substantial. Therefore, an improved system and method for supporting nozzle assemblies to reduce the effects of creep would be useful.